The present invention relates to a lower cost, higher efficiency combination burner which fires on natural gas, fuel oil and liquid propane gas with lower CO emissions and high flame stability.
Conventional combination burners such as shown, for example, in U.S. Pat. Nos. 5,259,755 and 5,700,143, assigned to the assignee of the present application, experience one or more of the following conditions:
(1) high CO and unburned hydrocarbon emission;
(2) inadequate flame shaping to match the size of the available combustion space;
(3) low efficiency;
(4) flame instability oil when using compressed air atomization;
(5) bulky burners package size.
These shortcomings have long been known in the combustion industry but efforts by various sources to overcome them in one burner have been unsuccessful. For example, the xe2x80x9cECOSTARxe2x80x9d burner made by the Hauck Manufacturing Company, said assignee, achieved natural gas stability with an enlarged flame holding area but did not achieve other desired goals.
An object of the present invention has been to solve the problems and shortcomings encountered in conventional combination burners.
This object has been achieved by providing a combination burner of the general type shown in the above-referenced U.S. patents, whose disclosure is incorporated by reference herein, but in which a compact burner unit is configured with an adjustable and highly efficient spin section in the burner nose so as to provide substantially improved flame adjustability.
According to another aspect of the present invention, higher static air pressures are used to promote faster air/fuel mixing in natural gas, propane and oil so as to achieve higher flame intensities and thereby smaller flame volumes.
A still further aspect of the present invention involves achieving flame stability by enlarging the flame stabilization zone when the burner is on natural gas, ahd using an atomizer and diverting air ring on the primary air tube when the burner is on oil.
More specifically, the combination burner according to the present invention achieves these advantages by being provided, inter alia, with an adjustable and energy-efficient main air spin section located in the burner nose where it has been found to be most effective; a fixed secondary air spin section in the center; a higher pressure main air supply, via main air fan, to promote high exit velocities and fast mixing for higher combustion intensity; an air diverting ring to promote flame stability and eliminate overspray on oil firing; an enlarged gas stability point for improved flame stability on natural gas; a compressed air atomizer for oil firing; and a multiple propane nozzle for firing liquid propane.
The foregoing compact combustion burner provides lower CO emissions than in conventional burners, improves flame stability on natural gas, oil and propane, achieves faster mixing to improve combustion intensity, provides better flame shaping and adjustability and allows the use of modular manufacturing techniques.